SEATTLE — It’s going to be longer than expected before the Seattle Mariners can expect former All-Star righty Hisashi Iwakuma to return to their rotation.

Iwakuma won’t throw for 10 days to two weeks after reporting continuing tightness in a strained back muscle that surfaced April 21 — one day after his last start.

“It’s a tough situation.” he said. “I took about a week off, and then I started to throw for about a week. But I still felt something. It’s not pain. It more tightness. But we’re making sure that I feel nothing when I throw next time.”

Specifically, Iwakuma has a strained right latissimus dorsi muscle, which connects the arm to the back. The revised timetable makes it unlikely he will rejoin the rotation before mid-to-late June.

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“His rehab has not gone as well as we thought it would (go),” manager Lloyd McClendon said. “He’s still experiencing some stiffness…Anytime you have a lat strain, you’ve got to be careful.

“It just makes sense to back him off.”

Once Iwakuma is judged ready to resume throwing, he will likely follow the normal progression: playing catch, throwing long toss, throwing from a mound, a simulated game or two and at least two minor-league rehab starts.

“I was hoping I would be pain-free or feel nothing,” he said, “by the time I was scheduled to throw. But I was still feeling something inside. It is frustrating.”

ROTATION TWEAK

Hoping for more favorable match-ups, the Seattle Mariners are tweaking their rotation this week in order to steer left-hander Roenis Elias away from San Diego’s heavy right-handed lineup.

Monday’s open date in the schedule will permit right-hander Taijuan Walker to start Wednesday’s game against the Padres with his usual rest between starts.

Elias will shift back one day and pitch Thursday in the series opener against the Boston Red Sox at Safeco Field.

“It’s (also) about wanting to line up our lefties against Boston,” McClendon said. “It doesn’t hurt to have a righty against this club (the Padres) either.”

McClendon indicated Sunday that he was considering such a move to keep Elias away from a Padres’ lineup that includes Matt Kemp, Justin Upton and Wil Myers.

“San Diego likes to hit off left-handers,” McClendon said. “(It’s) nothing he’s done. Just trying to get the best matchup.”

The Mariners are already starting one lefty, James Paxton, in the two-game series against the Padres. He faced a San Diego lineup Tuesday that, including two switch-hitters, had nine right-handed hitters.

Missaki, 19, pitched seven innings of a combined May 1 no-hitter against Cedar Rapids. He was 1-2 with a 3.41 ERA in six starts. The Mariners signed him in 2013 after he pitched for Brazil in the World Baseball Classic.

Cleto, 22, hasn’t pitched since April 18 and had allowed three runs and five hits over 7 2/3 innings in three relief outings. A Dominican native, he signed with the Mariners in 2011 as a non-drafted free agent.

LOOKING BACK

It was 14 years ago Wednesday — May 13, 2001 — that Edgar Martinez scored the 1,000th run of his career.

He scored from second base on a two-out RBI single by Bret Boone against Esteban Loaiza in the first inning of a 7-5 victory at Toronto.

Martinez concluded his 18-year career in 2004 with a franchise-record 1,219 runs. Ichiro Suzuki ranks second at 1,176, followed by Ken Griffey Jr. at 1,113.

SHORT HOPS

The Mariners and Padres are considered “natural rivals” for scheduling purposes — the Vedder Cup! — despite being separated by approximately 1,050 miles. The second-longest distance between natural rivals is the 882 miles between Houston and Colorado…The Mariners’ bullpen allowed only two runs over 12 innings in the three-game weekend sweep over Oakland. The relief corps allowed 11 earned runs in 15 2/3 innings over the previous seven games.

ON TAP

The Mariners and Padres conclude their two-game series at 7:10 p.m. Wednesday at Safeco Field. Taijuan Walker (1-3, 8.13) was face San Diego’s James Shields (4-0, 4.25) in a matchup of right-handers.

About Bob Dutton

Bob Dutton joined The News Tribune in 2013 after more than 25 years at the Kansas City Star, including the last 13 covering baseball and the Royals. He was the president of the Baseball Writers' Association of America in 2008 and serves on the committee that nominates players to the Hall of Fame.